×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Fastener Flexibility Application for this Scenario

Fastener Flexibility Application for this Scenario

Fastener Flexibility Application for this Scenario

(OP)
Folks,
Let's say I want to calculate Shear Flexibility of a fastener/rivet in a joint using equation such as Huth for FE input.

The joint shown below is hypothetical but I want to learn on how to tackle a joint made of dissimilar materials & different thicknesses.



In the above joint, the fastener is under double shear. All the 3 plates in the joints are of different thicknesses & materials.

1. If I am modeling a FE using CBUSH element, do I need to two different Bush elements? One bush connecting Ti plate to Al plate & another one from Al to Steel plate? This is in spite of same fastener/rivet used to join all 3 plates together.

2. If the answer to the above question is yes, then I assuming that each Bush element will have its own shear spring constants definition as calculated using an appropriate fastener flexibility equation?

3. If the answer to (1) is NO, then how does one account for different materials & thicknesses in calculating flexibility.

Thanks in advance...

RE: Fastener Flexibility Application for this Scenario

you've all three plates modelled ? (say at mid-thickness)

then 2 CBUSH required.

equal stiffness (Huth for the joint) or two different stiffness (Huth for 1/2 AL + Steel, and 1/2 AL + Ti) … shouldn't make a significant difference

you can always hand calc the bolt shears later

another day in paradise, or is paradise one day closer ?

RE: Fastener Flexibility Application for this Scenario


I think you can use an equivalent section changing one material into one of the others using the ratio of elastic modulus ratio Of one material To the other, similar to calculating bending on a compound section.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

RE: Fastener Flexibility Application for this Scenario

(OP)
Rb1957 & desertfox, thanks for your replies.

RB, yes all 3 plates will be modeled @ Midsurface. Actually, the thought of dividing the middle plate (Al) in to half for top & bottom never crossed my mind. Very interesting...

Thanks again for your inputs...

RE: Fastener Flexibility Application for this Scenario

you might fuss over the proportioning between the plates … hand calc the relative stiffness of the steel and Ti plates, then proportion the Al plate similarly (if steel is taking 60% of the load, then give it 60% of the Al plate).

another day in paradise, or is paradise one day closer ?

RE: Fastener Flexibility Application for this Scenario

Nope, you need more than two CBUSH elements, because those will not enforce continuity of the fastener thru the joint. Google “Ruttman fastener modelling”

RE: Fastener Flexibility Application for this Scenario

Is the rivet solid steel ?
Or, a structural blind "pop" rivet etc ?

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close